Pembrolizumab (Keytruda, Merck), an anti-PD-1 therapy, has been approved by the FDA as a monotherapy for the treatment of patients with recurrent or metastatic cutaneous squamous cell carcinoma (cSCC). The recommended pembrolizumab doses for cSCC are 200 mg every 3 weeks or 400 mg every 6 weeks, according to the FDA approval.

Pembrolizumab is indicated for cases not curable by surgery or radiation. According to a Merck press release, cSCC is the second most common form of skin cancer. 

The FDA approval was based on the phase 2 KEYNOTE-629 trial. The study was composed of 105 patients with a median age of 72 years, the majority of whom were white (71%) and male (76%). Nearly three-quarters of the study population (74%) received prior radiation therapy and 87% received 1 or more prior lines of therapy, according to the press release. Pembrolizumab  was found to generate an objective response rate of 34%, a complete response rate of 4%, and a partial response rate of 31%. Of the responding patients, 69% had ongoing responses of 6 months or longer. 

“In KEYNOTE-629, treatment with Keytruda resulted in clinically meaningful and durable responses. Today’s approval is great news for patients with cSCC and further demonstrates our commitment to bringing new treatment options to patients with advanced, difficult-to-treat cancers,” Vice President of Clinical Research for Merck Research Laboratories Jonathan Cheng, MD, said in the press release. 

Immune-mediated adverse reactions such as pneumonitis, colitis, hepatitis, severe skin reactions, and endocrinopathies can occur from treatment with pembrolizumab, according to the press release. It can also cause infusion-related reactions, which may be life threatening. Additionally, it can cause fetal harm if the patient is pregnant. 

FDA Approves Merck’s KEYTRUDA® (pembrolizumab) for the Treatment of Patients with Recurrent or Metastatic Cutaneous Squamous Cell Carcinoma (cSCC) that is Not Curable by Surgery or Radiation (News Release); Kenilworth, NJ; June 24, 2020; Business Wire; Accessed June 25, 2020